Manufacture of water gas



Feb. 8, 1949. H. v. ATWELL MANUFACTURE OF' WATER GAS Filed July 24, 1945l VENTOR HIS ATTORNEY HAROLD V. ATWELL.

zomsl Patented Feb. 8, 1949 MANUFACTURE F WATER GAS Harold V. Atwell,Beacon, N. Y., assignor to The Texas Company, New York, N. Y., acorporation of Delaware Application July 24, 1943, Serial No. 496,012

4 Claims.

This invention relates to. a continuous method of manufacturing watergas involving reaction of carbon with steam to produce carbon monoxide.

In ac-cordance with the invention a solid carbonaceous material such ascoke' is converted to the form of a line powder and this fine powder isdispersed in a stream of air or other oxygenbearing gas capable ofsupporting combustion under conditions such that a small portion ofcarbon undergoes combustion, the heat of combustion being used to raisethe remainder of the powder to a temperature suitable for effecting theWater gas reaction.

A stream of heated powder is continuously withdrawn from a combustionzone and dispersed or suspended in a stream of' steam and the resultingfluid mixture passedv through a reaction zone wherein carbon isconverted to carbon monoxide. A gaseous stream of reaction productscontaining water gas and unconverted carbon powder suspended therein isdrawn off from the reaction zone. This withdrawn stream is passedthrough a separator wherein suspended powder is` separated from thegaseous products,'which latter are discharged from the system. Theseparated and unconverted powder is returned to the combustion zone.

An important advantage of the process of this invention resides in thecontinuity of flow as contrasted with the intermittent type of operationvused heretofore. Previously it has been the practice to charge a batchof coke or carbonaceous material to a reaction vessel and blast thecharge with air for a period of time suicient to raise the mass ofincandescence. Thereupon the ow of air is discontinued temporarily and astream of steam is passed through the highly heated mass of carbon underconditions such that carbon is oxidized to form carbon monoxide.4 Theflow of steam is continued through the hot mass until the temperature ofthe mass' is reduced to a point at which the water gas reaction is nolonger operative. Thereupon the flow of oxygen or air through the massis resumed so as to again restore it to a state of incandescence. Thepresent invention avoids this intermittent type of operation with itswidely fluctuating temperatures and so permits the continuous productionof a stream of carbon monoxide and hydrogen suitable as synthesis gasfor catalytic conversion into hydrocarbons or alcohols.

It permits continuously supplying to theA synthetic reaction, powderedcarbon at a uniform temperature level, preferably not substantially inexcess of about 1800 F. and below that temperature at which clinkerformation becomes a problem during either the combustion of the carbonor during the subsequent water gas reaction.

A feature of the invention resides in employing powdered carbon of ahigh degree of neness in the water gas reaction' stage. The carbonparticles are materially reduced in size as a result of partialcombustion in the combustion zone and this facilitates the subsequentwater gas reaction. Since unconverted powdered carbon leaving the watergas reaction stage is continuously recycled through the combustion zone,the decrease in particle size is progressive as a result of furtherburning action.

Dispersion of the powdered carbon in dust-like form in the air oroxygen-containing gas flowing through the combustion zone facilitatesrealizing partial though limited combustion of each individual carbonparticle so that the combustion results in uniformly decreasing the sizeof all carbon particles passing through the combustion zone.

In order to describe the invention further reference will now be made tothe accompanying drawing showing a flow diagram illustrative of onemethodV of practicing the process.

In the drawing the numeral I refers to a burner in the form of avertical vessel wherein the finely powdered carbon is brought intocontact with a stream of air or other oxygen-bearing gas capable ofsupporting combustion.

The stream of oxygen-bearing gas such as air is continuously, introducedto the bottom portion of the burner I through a pipe 2.

Coke or other solid carbonaceous material reduced to a line powder ofabout 10 to 100 mesh is drawn from a storage hopper 3 to a feed hopper 4which latter is immediately above the burner I and may be substantiallyintegral therewith. A suitable valve 5 is provided in the conduitconnecting the hopper 4 with the burner l through which the powderedcarbon is conducted into the upper portion of the burner.

The yrate of introduction of powder and also the rate of introduction ofair to the burner I' is regulated so that the powder is widely dispersedin the gases within the burner I. Conditions are maintained so that somecombustion of carbon occurs within the mass of gas and suspended carbonpowder. The proportion of carbon so burned ranges from about 20 to 40%by Weight of the total carbon powder introduced to the burner I.

'As a result of combustion the unconverted and.

major proportion of the carbon powder is raised a conduit I leading to adust separator Il wherein entrained carbon powder is separated bycentrifugal action or by other mechanisms which may involve electricalprecipitation.

At any rate the flue gas substantially free from carbon powder iscontinuously discharged through a pipe I2.

Since the efiiuent gas stream flowing through pipe Ill may contain asubstantial amount of ash, it is advantageous to provide dust separatingapparatus such that the entrained carbon powder is separately removedfrom the gas stream. 'I'he ash may remain in the gas stream fordischarge from the system through the pipe I2, or means may be providedto eect its removal in a separate stage, especially where the ei'iiuentgas is passed through waste heat recovery apparatus.

If desired all or a portion of the flue gas so discharged through pipeI2 may be by-passed through a branch pipe I3 leading to an exchanger Ilwherein the sensible heat of the flue gas is used to super-heat steamused in the conversion process.

Thus, steam may be conducted from a source not shown through a pipe I5communicating with the steam side of the exchanger I4 and from which thesuper-heated steam is conducted through a pipe I6.

While an exchanger has been mentioned, nevertheless it will beunderstood that a waste heat boiler may be substituted in which case itmay be used for converting a stream of water into super-heated steamwhich is passed into the pre' viously mentioned pipe IB.

The carbonaceous material separated from the ue gas in the separator I Iis dropped into a hopper I'I which also communicates through a standpipeI8 with the previously mentioned conduit 8. The standpipe IB is alsoprovided with a control valve I 9.

Steam is introduced from the pipe I 6 to the conduit 8 and as it owsthrough the conduit picksup the powdered carbon introduced from thestandpipes I8 or 6 or from both of them and the resulting suspension ofsteam and solid carbon particles is conducted through the conduit- -B toa lower portion of a water gas reactor 20.

The powdered carbon suspended in the stream of steam flowing through theconduit 8 is already at an elevated temperature in the range about 1500to 2000 F. and preferably in the range about 1500 to 1800 F., withinwhich the water gas reaction proceeds.

Consequently, during passage through the conduit 8 and the reactor 20,carbon undergoes conversion to carbon monoxide with accompanyingreduction of the steamto free hydrogen.

Thesteam and powdered carbon may be introduced to the conduit 8 inapproximately molecular proportions although if desired excess steam maybe present in order to facilitate transporting the hot particles ofcarbon powder into the reactor 20.

As previously indicated the powder is o! a high degree oi ilneness atthis stage and it is preferred to effect the water gas reaction in thesubstantial absence of particles having a diameter of as great as Vainch. Preferably the powder in this stage is at least suiiciently ne topass through a sieve of about 15 to 200 mesh.

The stream of water gas containing uncon verted carbon leaves thereactor 20 through a conduit 2l which leads to a separator 22 which maybe of the cyclone type.

The separator 22 eects separation between the gaseous products of thereaction and the suspended carbon powder. The gaseous products of thereaction comprising carbon monoxide and hydrogen as well as some ashwhich may be present are continuously discharged from the separator 22through 'a pipe 23, while the separated carbonaceous powder whichaccumulates in the bottom of the separator 22 and is substantially freeof ash, is continuously drawn oi! through a conduit 2l leading to thepreviously mentioned feed hopper 4.

In this way unconverted powdered carbon is recycled through the systemuntil completely consumed producing either ue gas or water gas as thecase may be. Once the system is in operation it is merely suiiicient toadd make-up carbonaceous powder from the hopper 3 in an amountsufficient to compensate for the continual disappearance of carbon fromthe system in the form of flue gas or water gas.

The water gas being discharged through the pipe 23 is passed' to aprecipitator or scrubber 25 adapted to eiect removal of ash. Electricalprecipitation or scrubbing with a liquid or spray may be used for thispurpose. The water gas may be subjected to purication treatments toremove sulfur compounds that may be present. The desuifurized water gasmay then be passed to a catalytic reaction zone wherein the carbonmonoxide is hydrogenated to produce synthetic hydrocarbons.

Obviously many modiiications and variations of the invention as aboveset forth may be made without departing from the spirit and scopethereof, and therefore only such limitations should be imposed as areindicated in the appended claims.

I claim:

1. A continuous method of producing carbon monoxide and hydrogen from asolid carbona ceous material which comprises converting said material tonely powdered form, introducing said powder to a vertical combustionzone, introducing to the lower portion of said zone a stream ofoxygen-containing gas, passing said gas upwardly through the combustionzone in contact with said powder so that powder is maintained dispersedin gas within said zone, effecting partial combustion of said powderwith accompanying decrease in particle size and formation of ash.discharging fromv the upper portion of said zone a stream of hotcombustion gas containing entrained hot carbonaceous particles and ash,separating entrained hot carbonaceous particles from said discharged gasand ash, passing said residual hot gas stream in indirect contact with astream of steam, injecting said separated hot particles in the resultingheatedstream of steam. continuously withdrawing hot carbonaceousparticles from the bottom of said combustion zone, inJecting saidwithdrawn hot carbonaceous particles into said heated stream of steam,passing the resulting hot mixture of steam and inlected particlesupwardly through a vertical reaction zone, reacting said carbonaceousparticles with steam at a temperature of about 1500 F. and above in saidreaction zone so as to form carbon monoxide and hydrogen, removing fromthe upper portion of said reaction zone an emuent steam of carbonmonoxide and hydrogen containing entrained particles of unconsumedcarbonaceous material and ash, separating en trained unconsumedcarbonaceous material from said carbon monoxide, hydrogen andash,`recycl ing separated unconsumed carbonaceous material to saidcombustion zone and separating ash from said effluent stream of gas soas to provide a gaseous mixture comprising mainly carbon monoxide andhydrogen.

2. A continuous method of producing carbon monoxide and hydrogen from asolid carbonaceous material which comprises converting said carbonaceousmaterial to nnely powdered form. continuously introducing said powder tothe upper portion of a vertical combustion zone, continuouslyintroducing to the lower portion of said zone a stream ofoxygen-containinggas, passing said gas upwardly through said combustionzone in contact with said powder so that powder is maintained dispersedin gas within said zone, eiecting partial combustion of said particleswith accompanying decrease in particle size, and formation oiash,discharging from the upperportion of said zone a stream of hotcombustion gas containing entrained hot carbonaceous particles and ash,separating said entrained carbonaceous exchange with steam so as tosuperheat thesteam, injecting said separatedhot particles in resultingsuperheated steam, continuously withdrawing carbonaceous particles fromthe bottom of said combustion zone at an elevated temperaturesubstantially above 1500 F., injecting said withdrawn carbonaceous'particles into said superheated stea passing resulting mixture ci" steamand injected particles upwardly through a vertical reaction zone,reacting said carbonaceous particles with steam at a temperature ofabout 1500 l". and above in said reaction zone so as to form carbonmonoxide and hydrogen. removing from the upper portion of said reactionzone an eilluent stream of carbon monoxide and hydrogen containingentrained particles of unconsumed vcarbonaceous material, separatingsaid unconsumed particles i from the eiliuent stream and recycling saidseparated unconsumed particles to said combustion zone.

3. The method according to claim 2 in which the carbonaceous material isconverted to a powder of about l0 to 100 mesh prior to its introductioninto the vertical combustion zone.

4. A continuous method of producing carbon monoxide and hydrogen from asolid carbonaceous material which comprises converting said carbonaceousmaterial to finely powdered form, introducing said powder to a verticalcombustion zone. continuously introducing to the lower portion oi' saidzone a stream of oxygen-contaming gas, passing said gas upwardly throughsaid combustion zone in contact with said powder so that powder ismaintained dispersed in gas within said zone, eilecting partialcombustion of said powder with accompanying decrease in particle sizeand formation oi' ash, discharging from the upper portion of said zone astream of hot combustion gas containing entrained hot carbonaceousparticles and ash, separating entrained hot carbonaceous particles fromsaid discharged gas and ash, suspending said separated hot particles insteam, continuously withdrawing hot carbonaceous particles from thebottom of said combustion zone, suspending said withdrawn hotcarbonaceous particles in said steam. passing resulting mixture of steamand particles suspended therein upwardly through a vertical reactionzone. reacting said carbonaceous particles with steam at a temperatureoi' about 1500 F. and above in said reaction zone so as to form carbonmonoxide and hydrogen, removing from the upper portion of the reactionzoneI an eilluent stream oi carbon monoxide and hydrogen containingentrained particles of unconsumed carbonaceous material, separating saidunconsumed particles from the eilluent stream and recycling separatedparticles to said combustion zone.

HAROLD V. ATWELL.

REFERENCES CITED The following references are of record in the ille ofthis patent:

FOREIGN PATENTE Number country nate 23,045 Great Britain, 1910 Aug 2,4,1911 318,016 Great Brit-am aus. 29, im 564,870 Germany Nov. a4, 1932escasa France oet. 1o, im

o'rnna nnli'riaiinciizs Haslam and Russell, "Fuels and Their Combustion,pp. 140, 60o-601.

